Fix: files contain columns that are not part of GTFS

Published: 3 July 2026. Last reviewed: 3 July 2026.

Code: unknown_column (MobilityData validator)

What this means

A file in your feed has a column header that is not a field in the GTFS spec. Apps ignore columns they do not recognise, so these do no harm on their own. The validator surfaces them because an unknown column is sometimes a misspelled real one, and that case does cause harm.

Why it matters

Two things hide behind an unknown column. The harmless kind is a vendor extra: an internal field the export carries that no app reads. The harmful kind is a typo in a standard field name, like stop_lat written stop_latt or wheelchair_boarding written wheelchair_boardng. When a real field is misspelled, every app treats it as missing, so the data you entered silently does nothing. The check is worth a look precisely because it catches that.

How to fix it

Look at each flagged column name:

• A misspelled GTFS field: correct the spelling so apps read the data again. Compare against the field names in the GTFS reference; the typo is usually one or two letters off a real field.
• A genuine vendor extra: it is safe to leave, but removing it keeps the feed clean and the next reviewer from wondering. Many tools have a setting to export only standard fields.

How long it usually takes

A quick look at the flagged files. Correcting a typo is a one-line change; deciding a column is a harmless extra takes only a glance.

Authoritative rule

unknown_column is a canonical MobilityData GTFS Validator notice used in validator reports across the GTFS ecosystem. Read the authoritative rule for unknown_column in the GTFS Validator rules. (opens on an external site)